The invention relates the processing of sheets in general, and more particularly to improvements in apparatus for positioning sheet-like covers on top of stacks of paper sheets or the like. Still more particularly, the invention relates to improvements in apparatus wherein covers (e.g., covers made of cardboard or plastic material) are placed on top of successive stacks of a series of moving stacks or superimposed paper sheets or the like.
It is often necessary to place a relatively stiff cover on top of a stack of superimposed paper sheets or other sheets. For example, a cover will be placed on top of a stack which consists of pressure-sensitive sheet-like forms or blanks before the stack is draped into a web of paper or the like.
Certain stationery products (such as pads) also require covers which are placed on top of and are secured (e.g., stapled or bonded) to stacks of aligned paper sheets. It is also known to assemble covers of blotting paper with stacked sheets of writing paper.
Presently known apparatus for positioning covers on top of stacks of papers sheets or the like employ conveyors which transport the stacks and the covers in the same direction, and complex aligning devices which are designed to ensure that each cover is properly aligned with the corresponding stack prior to attachment of the cover to the stack and/or prior to draping of the cover and the stack into a blank of paper, plastic foil or the like. The aligning operation must be carried out with utmost care because the appearance of the ultimate product (such as a writing pad) is greatly affected by the lack of proper alignment of the cover with the sheets of the stack. Moreover, it is difficult to properly pile stacks on top of each other or to properly wrap the stacks if their sheets are not accurately aligned with the respective cover or covers.